Wild caught Amazonian fish are typically hard to come by between the months of November to May. That's because it's the rainy season in the Amazon and therefore it's very difficult to catch fish, especially those that hide among the weeds, when the water levels rise 15 meters. This is now the beginning of the dry season, so as water levels drop, catching and exportation will increase.
One of the suspected reasons for Otto mortality is that the catchers often poison the waters with toxic substances in order to stun the fish. This makes it easier to catch them, but it also makes them ill.
Another reason is that holding tanks are scrubbed algae free, so that the fish do not have the opportunity to feed and to regain their strength. If they are not fed substitutes such as zucchini, then they are in bad shape. It is believed that this is why Ottos and several other species such as Cardinals exhibit the high mortality rate due to these combination of stresses, and that if they survive the first month or so then they are likely to carry on.
The best things when taking home Ottos therefore are to ensure that the water is kept as clean as possible and to ensure that they are fed immediately. If diatom algae is present this is a boon to them.
Cheers,
